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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
354 lines
9.1 KiB
C
354 lines
9.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Manage cache of swap slots to be used for and returned from
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* swap.
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*
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* Copyright(c) 2016 Intel Corporation.
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*
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* Author: Tim Chen <tim.c.chen@linux.intel.com>
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*
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* We allocate the swap slots from the global pool and put
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* it into local per cpu caches. This has the advantage
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* of no needing to acquire the swap_info lock every time
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* we need a new slot.
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*
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* There is also opportunity to simply return the slot
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* to local caches without needing to acquire swap_info
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* lock. We do not reuse the returned slots directly but
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* move them back to the global pool in a batch. This
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* allows the slots to coaellesce and reduce fragmentation.
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*
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* The swap entry allocated is marked with SWAP_HAS_CACHE
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* flag in map_count that prevents it from being allocated
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* again from the global pool.
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*
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* The swap slots cache is protected by a mutex instead of
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* a spin lock as when we search for slots with scan_swap_map,
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* we can possibly sleep.
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*/
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#include <linux/swap_slots.h>
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#include <linux/cpu.h>
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#include <linux/cpumask.h>
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#include <linux/vmalloc.h>
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#include <linux/mutex.h>
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#include <linux/mm.h>
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#ifdef CONFIG_SWAP
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static DEFINE_PER_CPU(struct swap_slots_cache, swp_slots);
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static bool swap_slot_cache_active;
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bool swap_slot_cache_enabled;
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static bool swap_slot_cache_initialized;
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DEFINE_MUTEX(swap_slots_cache_mutex);
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/* Serialize swap slots cache enable/disable operations */
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DEFINE_MUTEX(swap_slots_cache_enable_mutex);
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static void __drain_swap_slots_cache(unsigned int type);
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static void deactivate_swap_slots_cache(void);
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static void reactivate_swap_slots_cache(void);
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#define use_swap_slot_cache (swap_slot_cache_active && \
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swap_slot_cache_enabled && swap_slot_cache_initialized)
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#define SLOTS_CACHE 0x1
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#define SLOTS_CACHE_RET 0x2
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static void deactivate_swap_slots_cache(void)
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{
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mutex_lock(&swap_slots_cache_mutex);
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swap_slot_cache_active = false;
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__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
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mutex_unlock(&swap_slots_cache_mutex);
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}
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static void reactivate_swap_slots_cache(void)
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{
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mutex_lock(&swap_slots_cache_mutex);
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swap_slot_cache_active = true;
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mutex_unlock(&swap_slots_cache_mutex);
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}
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/* Must not be called with cpu hot plug lock */
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void disable_swap_slots_cache_lock(void)
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{
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mutex_lock(&swap_slots_cache_enable_mutex);
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swap_slot_cache_enabled = false;
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if (swap_slot_cache_initialized) {
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/* serialize with cpu hotplug operations */
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get_online_cpus();
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__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
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put_online_cpus();
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}
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}
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static void __reenable_swap_slots_cache(void)
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{
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swap_slot_cache_enabled = has_usable_swap();
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}
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void reenable_swap_slots_cache_unlock(void)
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{
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__reenable_swap_slots_cache();
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mutex_unlock(&swap_slots_cache_enable_mutex);
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}
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static bool check_cache_active(void)
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{
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long pages;
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if (!swap_slot_cache_enabled || !swap_slot_cache_initialized)
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return false;
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pages = get_nr_swap_pages();
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if (!swap_slot_cache_active) {
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if (pages > num_online_cpus() *
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THRESHOLD_ACTIVATE_SWAP_SLOTS_CACHE)
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reactivate_swap_slots_cache();
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goto out;
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}
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/* if global pool of slot caches too low, deactivate cache */
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if (pages < num_online_cpus() * THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE)
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deactivate_swap_slots_cache();
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out:
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return swap_slot_cache_active;
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}
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static int alloc_swap_slot_cache(unsigned int cpu)
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{
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struct swap_slots_cache *cache;
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swp_entry_t *slots, *slots_ret;
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/*
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* Do allocation outside swap_slots_cache_mutex
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* as kvzalloc could trigger reclaim and get_swap_page,
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* which can lock swap_slots_cache_mutex.
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*/
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slots = kvzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE,
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GFP_KERNEL);
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if (!slots)
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return -ENOMEM;
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slots_ret = kvzalloc(sizeof(swp_entry_t) * SWAP_SLOTS_CACHE_SIZE,
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GFP_KERNEL);
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if (!slots_ret) {
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kvfree(slots);
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return -ENOMEM;
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}
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mutex_lock(&swap_slots_cache_mutex);
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cache = &per_cpu(swp_slots, cpu);
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if (cache->slots || cache->slots_ret)
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/* cache already allocated */
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goto out;
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if (!cache->lock_initialized) {
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mutex_init(&cache->alloc_lock);
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spin_lock_init(&cache->free_lock);
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cache->lock_initialized = true;
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}
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cache->nr = 0;
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cache->cur = 0;
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cache->n_ret = 0;
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cache->slots = slots;
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slots = NULL;
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cache->slots_ret = slots_ret;
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slots_ret = NULL;
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out:
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mutex_unlock(&swap_slots_cache_mutex);
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if (slots)
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kvfree(slots);
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if (slots_ret)
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kvfree(slots_ret);
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return 0;
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}
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static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
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bool free_slots)
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{
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struct swap_slots_cache *cache;
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swp_entry_t *slots = NULL;
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cache = &per_cpu(swp_slots, cpu);
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if ((type & SLOTS_CACHE) && cache->slots) {
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mutex_lock(&cache->alloc_lock);
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swapcache_free_entries(cache->slots + cache->cur, cache->nr);
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cache->cur = 0;
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cache->nr = 0;
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if (free_slots && cache->slots) {
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kvfree(cache->slots);
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cache->slots = NULL;
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}
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mutex_unlock(&cache->alloc_lock);
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}
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if ((type & SLOTS_CACHE_RET) && cache->slots_ret) {
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spin_lock_irq(&cache->free_lock);
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swapcache_free_entries(cache->slots_ret, cache->n_ret);
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cache->n_ret = 0;
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if (free_slots && cache->slots_ret) {
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slots = cache->slots_ret;
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cache->slots_ret = NULL;
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}
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spin_unlock_irq(&cache->free_lock);
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if (slots)
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kvfree(slots);
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}
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}
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static void __drain_swap_slots_cache(unsigned int type)
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{
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unsigned int cpu;
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/*
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* This function is called during
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* 1) swapoff, when we have to make sure no
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* left over slots are in cache when we remove
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* a swap device;
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* 2) disabling of swap slot cache, when we run low
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* on swap slots when allocating memory and need
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* to return swap slots to global pool.
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*
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* We cannot acquire cpu hot plug lock here as
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* this function can be invoked in the cpu
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* hot plug path:
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* cpu_up -> lock cpu_hotplug -> cpu hotplug state callback
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* -> memory allocation -> direct reclaim -> get_swap_page
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* -> drain_swap_slots_cache
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*
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* Hence the loop over current online cpu below could miss cpu that
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* is being brought online but not yet marked as online.
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* That is okay as we do not schedule and run anything on a
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* cpu before it has been marked online. Hence, we will not
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* fill any swap slots in slots cache of such cpu.
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* There are no slots on such cpu that need to be drained.
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*/
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for_each_online_cpu(cpu)
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drain_slots_cache_cpu(cpu, type, false);
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}
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static int free_slot_cache(unsigned int cpu)
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{
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mutex_lock(&swap_slots_cache_mutex);
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drain_slots_cache_cpu(cpu, SLOTS_CACHE | SLOTS_CACHE_RET, true);
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mutex_unlock(&swap_slots_cache_mutex);
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return 0;
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}
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int enable_swap_slots_cache(void)
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{
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int ret = 0;
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mutex_lock(&swap_slots_cache_enable_mutex);
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if (swap_slot_cache_initialized) {
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__reenable_swap_slots_cache();
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goto out_unlock;
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}
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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "swap_slots_cache",
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alloc_swap_slot_cache, free_slot_cache);
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if (WARN_ONCE(ret < 0, "Cache allocation failed (%s), operating "
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"without swap slots cache.\n", __func__))
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goto out_unlock;
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swap_slot_cache_initialized = true;
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__reenable_swap_slots_cache();
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out_unlock:
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mutex_unlock(&swap_slots_cache_enable_mutex);
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return 0;
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}
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/* called with swap slot cache's alloc lock held */
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static int refill_swap_slots_cache(struct swap_slots_cache *cache)
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{
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if (!use_swap_slot_cache || cache->nr)
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return 0;
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cache->cur = 0;
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if (swap_slot_cache_active)
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cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, false,
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cache->slots);
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return cache->nr;
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}
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int free_swap_slot(swp_entry_t entry)
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{
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struct swap_slots_cache *cache;
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cache = raw_cpu_ptr(&swp_slots);
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if (use_swap_slot_cache && cache->slots_ret) {
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spin_lock_irq(&cache->free_lock);
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/* Swap slots cache may be deactivated before acquiring lock */
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if (!use_swap_slot_cache || !cache->slots_ret) {
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spin_unlock_irq(&cache->free_lock);
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goto direct_free;
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}
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if (cache->n_ret >= SWAP_SLOTS_CACHE_SIZE) {
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/*
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* Return slots to global pool.
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* The current swap_map value is SWAP_HAS_CACHE.
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* Set it to 0 to indicate it is available for
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* allocation in global pool
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*/
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swapcache_free_entries(cache->slots_ret, cache->n_ret);
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cache->n_ret = 0;
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}
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cache->slots_ret[cache->n_ret++] = entry;
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spin_unlock_irq(&cache->free_lock);
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} else {
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direct_free:
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swapcache_free_entries(&entry, 1);
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}
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return 0;
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}
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swp_entry_t get_swap_page(struct page *page)
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{
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swp_entry_t entry, *pentry;
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struct swap_slots_cache *cache;
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entry.val = 0;
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if (PageTransHuge(page)) {
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if (IS_ENABLED(CONFIG_THP_SWAP))
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get_swap_pages(1, true, &entry);
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return entry;
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}
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/*
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* Preemption is allowed here, because we may sleep
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* in refill_swap_slots_cache(). But it is safe, because
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* accesses to the per-CPU data structure are protected by the
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* mutex cache->alloc_lock.
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*
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* The alloc path here does not touch cache->slots_ret
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* so cache->free_lock is not taken.
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*/
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cache = raw_cpu_ptr(&swp_slots);
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if (check_cache_active()) {
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mutex_lock(&cache->alloc_lock);
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if (cache->slots) {
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repeat:
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if (cache->nr) {
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pentry = &cache->slots[cache->cur++];
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entry = *pentry;
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pentry->val = 0;
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cache->nr--;
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} else {
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if (refill_swap_slots_cache(cache))
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goto repeat;
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}
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}
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mutex_unlock(&cache->alloc_lock);
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if (entry.val)
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return entry;
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}
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get_swap_pages(1, false, &entry);
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return entry;
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}
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#endif /* CONFIG_SWAP */
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